Reid Detmers, right?

On Wednesday evening, the Angels’ 24-year-old lefty had arguably his worst start of the season so far: 5 1/3 innings against the Rays, with seven hits and two runs (one earned) allowed, and only four strikeouts. Worst start of the season so far. One earned run.

After Wednesday night’s action, Detmers led all qualified major league starters in FIP, at 1.61, and shared the lead in pitching WAR. His 1.19 ERA was seventh in the majors. And his success has come against reasonable competition; in four starts, all Angels wins, he’s faced the Rays, the Red Sox (twice), and the Orioles. That first start in Baltimore came in Game 3 of the Angels’ season; in Games 1 and 2, Baltimore had smeared Patrick Sandoval and Griffin Canning all over the park like mosquito viscera on a truck driver’s windshield. Detmers held the Orioles hatchlings to a single run over five innings.

It’s not like this came out of nowhere. Detmers, despite his youth, is in his fourth major league season. He was a top-10 pick in 2020, yet another in a line of college ballplayers drafted by the Angels in a desperate attempt to squeeze a single winning season out of the Ohtani-Trout era. (It didn’t work.) Detmers has been at least an average starter for the past two seasons; he made 53 starts across 2022 and 2023, totaling 277 2/3 innings, and boasts an ERA- of 99 along with 4.7 WAR. He’s thrown a no-hitter!

So we know this isn’t some scrub having the best three weeks of his life. But is Detmers actually the frontline starter he’s resembled so far in 2024?

When a pitcher’s numbers take a jump like this, the first place to look is the underlying stuff. Is he throwing a new pitch? Has he tweaked his breaking ball? Is he changing the proportion in which he throws his pitches?

According to this Sam Blum article in The Athletic, featuring interviews with both Detmers and pitching coach Barry Enright, quite a bit has changed. Detmers has moved his position on the rubber and changed his slider grip from a spike grip to a more orthodox hand position.

Indeed, the slider is quite different from either last year’s slider or the sweeper that he tested at times in 2022 and 2023. This pitch is more in line with his 2022 slider: mid-80s rather than upper-80s, with more movement on both axes. That’s great, but it’s not one of the two things that interest me.

Detmers has gotten a lot better against right-handed batters. A lot better. Which, I know, platoon splits over four starts, small sample, blah blah blah, and all of that is true. But consider that getting opposite-handed hitters out is the most important thing a left-handed pitcher can do. Most of the league is right-handed. It’s not Detmers’ fault — it’s generations of people thinking lefties are demonically possessed; maybe in 50 years it’ll be easier to find left-handed scissors. But until then, Detmers has two options: First, find a time machine, travel back to before the three-batter minimum, and get comfortable living that Randy Choate life. Or second, get right-handed hitters out reliably.

Until September of last year, Detmers tried to do that with his breaking balls. In 2023 overall, he threw only 6.6% changeups to righties. But in September, he started throwing the cambio almost a quarter of the time against righties, and in 2024 that proportion has remained more or less stable.

Just based on raw movement numbers, Detmers’ changeup is pretty unimpressive. But it tunnels extremely well with his fastball, and with an average velocity difference of nine miles an hour between the two, that’s a tricky velocity differential for hitters to cover.

But if this is the secret to Detmers’ newfound success, it’s not showing up in the numbers against his secondary stuff. It’s showing up in his fastball numbers, which have gone from below-average to around the top-10 among qualified starters.

So what’s different here? Two things. Maybe three.

First, Detmers has made a subtle change to his fastball. In the past two seasons, it’s had pedestrian vertical movement numbers but well-above-average arm-side run. This season, he’s sacrificed two or three inches of run to get a similar amount of rise; if you’re thinking about movement from the pitcher’s perspective, it’s gone from about 11 o’clock to a quarter to noon.

Arm-side run is great, if you’re using it to pull the string on hitters and get them to swing at pitches on the fringes of the zone, or outside of it altogether. That’s not really what Detmers was doing last year.

Last year, Detmers would throw his fastball at the top of the zone and it’d kind of just sit there. With his new, more vertically oriented movement, this is what he’s doing with his fastball in 2024.

So instead of throwing the fastball down in the zone and watching it move across opponents’ bats, Detmers is throwing the fastball at the very top of the zone and watching it move up and out of reach.

I went looking for some kind of empirical backing for the effect this has had on swing and whiff rates, and found that 11.1% of Detmers’ fastballs at or above the strike zone had garnered a swing, nearly double the rate on similar pitches from last year. “That’s pretty solid,” I thought, and then I realized I’d forgotten to check a couple boxes on Baseball Savant. Turns out that one out of every nine pitches Detmers throws, total, is a fastball that gets a whiff at the top of the zone or above. The real numbers are even more impressive.

In the Sam Blum article I mentioned earlier, Enright talks about training Detmers to throw with confidence. “Big balls,” in the words of Enright (and also Bon Scott, the late-20th century Australian poet and composer).

Which makes Detmers the synthesis of two other pitchers I’ve written about recently: Max Fried and Lance Lynn. You just have to pitch with confidence and avoid throwing fastballs right down the chute. See? This job isn’t that complicated after all.

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